Vehicle air conditioning systems comprising refrigerant recovery vessels and methods for operating such systems

ABSTRACT

An air conditioning system for a vehicle including a vapor compression-type refrigerating cycle and using combustible refrigerant includes a refrigerant recovery vessel in communication with a gas-liquid separator and which of recovers the combustible refrigerant by the communication with the gas-liquid separator, and a valve which controls the communication between the refrigerant recovery vessel and the gas-liquid separator in response to an external signal. When combustible refrigerant is used as refrigerant of a vapor compression-type, refrigerating cycle, leakage of the refrigerant may be reduced, minimized, or eliminated, and the recovery of the refrigerant may be carried out readily and efficiently without requiring significant changes to the system configuration.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to vehicle air conditioning systemsincluding a vapor compression-type, refrigerating cycle and usingcombustible refrigerant, and, more specifically, to vehicle airconditioning systems having a mechanism which recovers refrigerant fromthe refrigerating cycle into a refrigerant recovery vessel, as needed.

2. Description of Related Art

In a known, vehicle air conditioning system, for example, in whichFreon® refrigerant, commercially available from E.I. DuPont De Nemoursand Co., of Wilmington Del. USA, such as HFC 134a refrigerant, is usedas the refrigerant for a vapor compression-type refrigerating cycle,even if the refrigerant leaks, because it is incombustible, there islittle or no risk of fire or explosion. Generally, such leaks are notconsidered to create significant risks.

Recently, in order to deal with global environmental concerns, muchattention has been paid to the use of a vapor compression-type,refrigerating cycle using refrigerant having a low, heat coefficient. Asa possible low heat coefficient refrigerant, natural systemrefrigerants, such as CO₂ and combustible refrigerants have beenproposed. Nevertheless, in a known air conditioning system for vehicles,in which refrigerant in a vapor compression-type, refrigerating cycle ischanged to combustible refrigerant, if the refrigerant leaks, there maybe some risk of fire or explosion because the refrigerant iscombustible, and, therefore, it is considered preferable to takemeasures to reduce, minimize, or eliminate the conditions favorable tosuch risks.

Although it does not relate to an air conditioning system for vehicles,a structure is known wherein a vessel is provided for recoveringcombustible refrigerant via the opening and closing operation of anelectromagnetic valve of a vapor compression-type, refrigerating cycleusing combustible refrigerant. See Japanese Patent Application No.JP-A-2000-171130 (“JP'130”). In the structure described in JP'130,however, because a pipe diverges from a refrigerant pipe between anexpansion valve and an evaporator, and because a refrigerant recoveryvessel is connected to the divergent pipe, even if this structure isapplied to an air conditioning system for vehicles, a design change oralteration of the system would be required and is not easily applied.Further, it may not always be possible to efficiently recoverrefrigerant by extracting combustible refrigerant from the pipe providedbetween an expansion valve and an evaporator.

SUMMARY OF THE INVENTION

Accordingly, a need has arisen for an air conditioning system forvehicles which may recover refrigerant while reducing, minimizing, oreliminating leakage of the refrigerant and which may recover therefrigerant readily and efficiently without requiring significantchanges to the system configuration, when combustible refrigerant isused as the refrigerant in a vapor compression-type, refrigeratingcycle.

To achieve the foregoing and other objects, an air conditioning systemfor vehicles comprising a vapor compression-type refrigerating cycle,which uses combustible refrigerant and comprises a gas-liquid separator,according to the present invention, comprises a refrigerant recoveryvessel in communication with the gas-liquid separator and which recoverscombustible refrigerant in the refrigerating cycle by the communicationwith the gas-liquid separator. Further, the system comprises a valvewhich controls the communication between the refrigerant recovery vesseland said gas-liquid separator in response to an external signal.

In this air conditioning system, it is preferred that the gas-liquidseparator and the refrigerant recovery vessel are integral to eachother. Further, the valve may be integral with the gas-liquid separatorand the refrigerant recovery vessel. Alternatively, a communication pathfor communicating between the gas-liquid separator and the refrigerantrecovery vessel may be disposed at a position outside of the gas-liquidseparator and the refrigerant recovery vessel, and the valve is disposedin the communication path.

Various structures may be employed to control refrigerant recovery. Forexample, a structure may be employed wherein a time period forrecovering refrigerant by opening the valve is set at a predeterminedtime period, and after expiration of the predetermined time period,recovered refrigerant is enclosed by closing the valve. Further, astructure may be employed wherein a pressure detecting device detects avessel pressure in the refrigerant recovery vessel or a separatorpressure in the gas-liquid separator, when refrigerant is recovered byopening the valve, the valve then is closed in accordance with adetected pressure by the pressure detecting device. In this structure,when refrigerant has been recovered by opening the valve, the valve thenmay be closed when a detected pressure by the pressure detecting deviceequals or exceeds a predetermined pressure. Further, a structure may beemployed wherein a vehicle collision detection device detects orpredicts a vehicle collision, and when the vehicle collision is detectedor predicted by the vehicle collision detection device, refrigerant inthe gas-liquid separator is recovered into the refrigerant recoveryvessel by opening the valve. Still further, a structure may be employedwherein a refrigerant leakage detection device detects a leakage ofrefrigerant in the refrigerating cycle, and when the refrigerant leakageis detected by the refrigerant leakage detection device, refrigerant inthe gas-liquid separator is recovered into the refrigerant recoveryvessel by opening the valve.

In addition, it is preferred that, when refrigerant in the gas-liquidseparator is recovered into the refrigerant recovery vessel by openingthe valve, a compressor provided in the refrigerating cycle is stopped.

Moreover, it is preferred that the valve is a valve driven by anelectromagnetic solenoid and that the normally, closed-type valve isopened when the electromagnetic solenoid is energized.

In another embodiment, a method is provided for controlling leakage ofrefrigerant in an air conditioning system for vehicles comprising agas-liquid separator, a refrigerant recovery vessel, and a selectivelyopenable communication path therebetween. The method comprises the stepsof: preselecting a predetermined parameter for stopping refrigerantrecovery; detecting a leakage of refrigerant within a refrigerantcircuit of the air conditioning system; opening said communication pathbetween said liquid-gas separator and the refrigerant recovery vessel;and closing the communication path when a measured parameter equals orexceeds the predetermined parameter.

In still another embodiment, a method is provided for controllingleakage of combustible refrigerant in an air conditioning system forvehicles comprising a gas-liquid separator, a refrigerant recoveryvessel, and a selectively openable communication path therebetween. Themethod comprising the steps of: preselecting a predetermined parameterfor stopping refrigerant recovery; detecting or predicting a vehiclecollision; opening the communication path between the liquid-gasseparator and the refrigerant recovery vessel; and closing saidcommunication path when a measured parameter equals or exceeds thepredetermined parameter. In these methods, the predetermined parametermay be a predetermined time period during which the communication pathis open or a predetermined pressure within the refrigerant recoveryvessel, such that the communication path is open when a pressuremeasured within the refrigerant recovery vessel is less than thepredetermined pressure. Further, the air conditioning system maycomprise a compressor, and these methods may comprise the step ofstopping the compressor when the communication path is open.

In the air conditioning system for vehicles according to the presentinvention, which air conditioning system uses combustible refrigerant asthe refrigerant in a vapor compression-type, refrigerating cycle, therefrigerant may be recovered readily and efficiently without requiringsignificant changes to the system configuration and substantially at aspecification of the present system, and leakage of the combustiblerefrigerant to outside may be reduced, minimized, or eliminated.Therefore, the risk of fire or explosion due to leakage of combustiblerefrigerant may be reduced, minimized, or eliminated.

Other objects, features, and advantages of the present invention will beapparent to persons of ordinary skill in the art from the followingdetailed description of preferred embodiments of the present inventionand the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, the needssatisfied thereby, and the objects, features, and advantages thereof,reference now is made to the following description taken in connectionwith the accompanying drawings.

FIG. 1 is a schematic diagram of an air conditioning system for vehiclesaccording to an embodiment of the present invention.

FIG. 2 is a vertical, cross-sectional view of a refrigerant recoveryvessel integral with a gas-liquid separator in the system depicted inFIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 depicts an air conditioning system 100 for vehicles according toan embodiment of the present invention. FIG. 2 depicts a refrigerantrecovery vessel 8 integral with a gas-liquid separator 7 used in system100 depicted in FIG. 1. In FIG. 1, air conditioning system 100 comprisesa vapor compression-type, refrigerating cycle 1 using combustiblerefrigerant. In vapor compression-type, refrigerating cycle 1, acompressor 3 is driven by an engine (or motor) 2 of a vehicle, which isa variable displacement compressor adapted to alter or adjust itsdisplacement or a fixed displacement compressor. The driving force fromengine 2 is transmitted, for example, via an electromagnetic clutch (notshown), and the ON/OFF operation of the electromagnetic clutch iscontrolled via a clutch controller 4. Compressor 3 may form part of arefrigerating cycle regardless of the presence or absence of such aclutch, and further, the control method of displacement (e.g., adjustingthe swash plate angle or varying compressor speed) is not particularlylimited. Refrigerant compressed to a relatively high temperature andpressure by compressor 3 is cooled at a condenser 6 having a fan 5 byexchanging heat with outside air, and the refrigerant is condensed andsubstantially liquefied. Refrigerant exiting condenser 6 is separatedinto a gaseous-phase portion and a liquid-phase portion by gas-liquidseparator 7, and in this embodiment, as described below, gas-liquidseparator 7 is integral with refrigerant recovery vessel 8. Anelectronic solenoid 10 and a pressure sensor 11 are provided to anintegral, refrigerant recovery vessel and gas-liquid separator device 9.The liquid refrigerant separated by gas-liquid separator 7 is reduced inpressure and expanded by an expansion valve 12, and, thereafter, is sentto an evaporator 13 as a cooling medium, and heat is exchanged with airsent through an air duct 14. The refrigerant evaporated in evaporator 13then is drawn into compressor 3, and again compressed. The evaporatorexit temperature is controlled by a displacement control signal sent tocompressor 3 or by ON/OFF control of the electromagnetic clutch viaclutch controller 4.

A blower 15 is disposed in air duct 14 through which air passes for airconditioning of a vehicle interior. An inside air introduction port 16and an outside air introduction port 17 are provided at an entrance ofair duct 14, and a switching damper 18 controls the amount of air drawnfrom both ports 16 and 17, and the drawn air then is sent towardevaporator 13 by blower 15. A portion of this drawn air having passedthrough evaporator 13 then is sent to heater 19 disposed downstream ofevaporator 13. The amount of air having passed through evaporator 13 andthrough heater 19 may be adjusted by an air mixing damper 20 to vary theamount of air having passed through evaporator 13 and bypassed heater19. The degree to which air mixing damper 20 is opened may be adjustedby an air mixing damper actuator 21. In this embodiment, at the exitside of evaporator 13, an evaporator exit air temperature sensor 22detects the temperature of air having passed through evaporator 13, anda refrigerant leakage detection sensor 23 detects leakage of refrigerantfrom refrigerating cycle 1 at this position. Refrigerant leakagedetection sensor 23 may be disposed at another desired position, andfurther, another refrigerant leakage detection sensor may be added atanother appropriate position. Air conditioning system 100 also maycomprise respective air discharge ports 24, 25, and 26 downstream ofevaporator 13 within air duct 14, such as air discharge ports for aDEFROST mode, a VENT mode, and a FOOT mode. Air discharge ports 24, 25,and 26 may be selected, and their opening and closing may be controlledby dampers 27, 28, and 29, respectively.

Air conditioning system 100 also may comprise a main controller 30. Thesignals from the above-described evaporator exit air temperature sensor22 and refrigerant leakage detection sensor 23 are sent to maincontroller 30. Further, in this embodiment, a signal indicating enginerotational speed 31, a signal indicating vehicle running speed 32, asignal indicating detected pressure from the above-described pressuresensor 11, a signal indicating detected interior temperature from avehicle interior temperature sensor 33, a signal indicating detectedoutside temperature from an outside air temperature sensor 34, a signalindicating the intensity of sunshine integral, from a sunshine sensor35, and a signal from a collision sensor 36 provided as a vehiclecollision detection device capable of detecting or predicting a vehiclecollision may be sent to main controller 30. Further, from maincontroller 30, a clutch signal 37 may be sent to clutch controller 4, adisplacement control signal 38 may be sent to compressor 3, and anelectromagnetic valve control signal 39 may be sent to electromagneticsolenoid 10, respectively.

FIG. 2 depicts an example of the structure of integral, refrigerantrecovery vessel and gas-liquid separator device 9. A desiccant 40 and afilter 41 are disposed in an upper portion of gas-liquid separator 7,and liquid refrigerant 43 is stored in a space 42 below the filter 41.Refrigerant is introduced into this upper portion through an inlet tube51, and liquid refrigerant 43 is discharged from liquid refrigerantstoring space 42 through an outlet tube 52. Although this structure maynot differ significantly from a known, gas-liquid separator, in thisembodiment, refrigerant recovery vessel 8 is added to integral device 9below gas-liquid separator 7 (at a position below liquid refrigerantstoring space 42). An electromagnetic valve 45 with a valve 44 operatedby electromagnetic solenoid 10 is disposed between liquid refrigerantstoring space 42 and refrigerant recovery vessel 8, and communicationbetween liquid refrigerant storing space 42 and refrigerant recoveryvessel 8 is controlled by the operation of valve 44 in response to anelectromagnetic valve control signal 39 sent from main controller 30 toelectromagnetic solenoid 10. In particular, when valve 44 is opened,liquid refrigerant 43 in liquid refrigerant storing space 42 is drawninto refrigerant recovery vessel 8, and when valve 44 is closed, liquidrefrigerant 43 is no longer drawn into refrigerant recovery vessel 8.Valve 44 is a normally closed-type valve (e.g., electromagnetic valve)which is opened when electromagnetic solenoid 10 is energized.

With respect to the method for recovering combustible refrigerant in theair conditioning system thus constructed, examples of two embodimentsare explained as follows.

In a first embodiment, when a vehicle collision is detected or predictedby collision sensor 36 provided as a vehicle collision detection device,electromagnetic solenoid 10 is energized, and combustible refrigerant ingas-liquid separator 7 is drawn into refrigerant recovery vessel 8.Further, in this recovery, when the pressure detected by pressure sensor11 equals or exceeds a predetermined value, or, when a predeterminedtime period expires, electromagnetic solenoid 10 is de-energized,thereby stopping the refrigerant recovery.

In a second embodiment, when a refrigerant leakage is detected byrefrigerant leakage detection sensor 23 provided in air conditioningsystem 100, electromagnetic solenoid 10 is energized, and combustiblerefrigerant in gas-liquid separator 7 is drawn into refrigerant recoveryvessel 8. Further, in this recovery, when the pressure detected bypressure sensor 11 equals or exceeds a predetermined value, or, when apredetermined time period expires, electromagnetic solenoid 10 isde-energized, thereby stopping the refrigerant recovery.

When the above-described embodiments of recovery operations are carriedout, the drive of compressor 3 is preferably stopped.

Thus, when there is a risk that combustible refrigerant leaks outside ofthe refrigerating cycle, or when leakage actually occurs, in order toprevent leakage of a significant amount of refrigerant, the combustiblerefrigerant is recovered quickly into refrigerant recovery vessel 8.Consequently, the amount of refrigerant leakage may be reduced,minimized, or eliminated, and the ability of the system to reduce therisk of fire or explosion may be significantly enhanced. In thisstructure, as described above, because integral, refrigerant recoveryvessel and gas-liquid separator device 9 may be disposed at a positionsimilar to that at which known, gas-liquid separators have beendisposed, the refrigerant recovery may be carried out readily andefficiently without requiring significant changes to the systemconfiguration.

Although refrigerant recovery vessel 8 is integral with gas-liquidseparator 7 in the above-described embodiment, these components may beformed separately. Further, a structure may be employed wherein thecommunication between gas-liquid separator 7 and refrigerant recoveryvessel 8 is not enclosed within integral, refrigerant recovery vesseland gas-liquid separator device 9. An external communication path may beprovided, and a valve, such as an electromagnetic valve, may be providedin the external communication path.

The present invention may be applied to any vehicle air conditioningsystem comprising a vapor compression-type, refrigerating cycle andusing combustible refrigerant, thereby realizing an air conditioningsystem for vehicles with a significantly reduced risk of fire orexplosion, even if combustible refrigerant is used.

While the invention has been described in connection with preferredembodiments, it will be understood by those skilled in the art thatvariations and modifications of the preferred embodiments describedabove may be made without departing from the scope of the invention.Other embodiments will be apparent to those skilled in the art from aconsideration of the specification or from a practice of the inventiondisclosed herein. It is intended that the specification and thedescribed examples are considered exemplary only, with the true scope ofthe invention indicated by the following claims.

1. An air conditioning system for vehicles comprising a vaporcompression-type, refrigerating cycle, which uses combustiblerefrigerant and comprises a gas-liquid separator, comprising; arefrigerant recovery vessel in communication with said gas-liquidseparator and which recovers said combustible refrigerant in saidrefrigerating cycle by the communication with said gas-liquid separator;and a valve which controls the communication between said refrigerantrecovery vessel and said gas-liquid separator in response to an externalsignal.
 2. The air conditioning system of claim 1, wherein saidgas-liquid separator and said refrigerant recovery vessel are integralto each other.
 3. The air conditioning system of claim 2, wherein saidvalve is integral with said gas-liquid separator and said refrigerantrecovery vessel.
 4. The air conditioning system of claim 1, wherein acommunication path for communicating between said gas-liquid separatorand said refrigerant recovery vessel is disposed at a position outsideof said gas-liquid separator and said refrigerant recovery vessel, andsaid valve is disposed in said communication path.
 5. The airconditioning system of claim 1, wherein a time period for recoveringrefrigerant by opening said valve is set at a predetermined time period,and after expiration of said predetermined time period, recoveredrefrigerant is enclosed by closing said valve.
 6. The air conditioningsystem of claim 1, further comprising a pressure detecting device, whichdetects a pressure in said refrigerant recovery vessel or in saidgas-liquid separator, and when refrigerant is recovered by opening saidvalve, said valve is closed in accordance with a detected pressure bysaid pressure detecting device.
 7. The air conditioning system of claim6, wherein said valve is closed when a detected pressure by of saidpressure detecting device equals a predetermined pressure.
 8. The airconditioning system of claim 1, further comprising a vehicle collisiondetection device, which detects or predicts a vehicle collision, andwhen the vehicle collision is detected or predicted by said vehiclecollision detection device, refrigerant in said gas-liquid separator isrecovered into said refrigerant recovery vessel by opening said valve.9. The air conditioning system of claim 1, further comprising arefrigerant leakage detection device, which detects a leakage ofrefrigerant in said refrigerating cycle, and when the refrigerantleakage is detected by said refrigerant leakage detection device,refrigerant in said gas-liquid separator is recovered into saidrefrigerant recovery vessel by opening said valve.
 10. The airconditioning system of claim 1, wherein, when refrigerant in saidgas-liquid separator is recovered into said refrigerant recovery vesselby opening said valve, a main controller stops a compressor provided insaid refrigerating cycle.
 11. The air conditioning system of claim 1,wherein said valve is a valve driven by an electromagnetic solenoid andsaid normally, closed-type valve is opened when said electromagneticsolenoid is energized.
 12. A method for controlling leakage ofrefrigerant in an air conditioning system for vehicles comprising agas-liquid separator, a refrigerant recovery vessel, and a selectivelyopenable communication path therebetween, said method comprising thesteps of: preselecting a predetermined parameter for stoppingrefrigerant recovery; detecting a leakage of refrigerant within arefrigerant circuit of said air conditioning system; opening saidcommunication path between said liquid-gas separator and saidrefrigerant recovery vessel; and closing said communication path when ameasured parameter equals or exceeds said predetermined parameter. 13.The method of claim 12, wherein said predetermined parameter is apredetermined time period during which said communication path is open.14. The method of claim 12, wherein said predetermined parameter is apredetermined pressure within said refrigerant recovery vessel, suchthat said communication path is open when an pressure measured withinsaid refrigerant recovery vessel is less than said predeterminedpressure.
 15. The method of claim 12, wherein said air conditioningsystem comprises a compressor, and the method further comprises the stepof stopping said compressor when said communication path is open.
 16. Amethod for controlling leakage of combustible refrigerant in an airconditioning system for vehicles comprising a gas-liquid separator, arefrigerant recovery vessel, and a selectively openable communicationpath therebetween, said method comprising the steps of: preselecting apredetermined parameter for stopping refrigerant recovery; detecting orpredicting a vehicle collision; opening said communication path betweensaid liquid-gas separator and said refrigerant recovery vessel; andclosing said communication path when a measured parameter equals orexceeds said predetermined parameter.
 17. The method of claim 16,wherein said predetermined parameter is a predetermined time periodduring which said communication path is open.
 18. The method of claim16, wherein said predetermined parameter is a predetermined pressurewithin said refrigerant recovery vessel, such that said communicationpath is open when a pressure measured within said refrigerant recoveryvessel is less than said predetermined pressure.
 19. The method of claim16, wherein said air conditioning system comprises a compressor and themethod further comprises the step of stopping said compressor when saidcommunication path is open.